Alkaline primary battery and battery manufacturing method

Abstract

To improve a discharge performance.SOLUTION: A battery 1 comprises: a positive electrode 3 that contains manganese dioxide and a graphite; a negative electrode 5 that contains zinc; an electrolyte into which the positive electrode 3 and the negative electrode 5 are immersed; and a polyethyleneimine that is contained in the negative electrode 5 or the electrolyte.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The technology of the present disclosure relates to batteries and battery manufacturing methods.

Background Art

[0002] Alkaline dry batteries containing polyethyleneimine in the positive electrode are known (Patent Document 1). Such alkaline dry batteries can improve the strength of the positive electrode, the slipperiness and dispersibility of the positive electrode mixture, and the yield and productivity. Also, alkaline dry batteries in which a chelating agent is added to the negative electrode are known (Patent Documents 2 to 3). In such alkaline dry batteries, zinc ions generated by discharge form complex ions with the chelating agent, thereby suppressing the growth of zinc oxide dendrites and preventing the dendrites from penetrating the separator and short-circuiting the positive electrode and the negative electrode. For this reason, such alkaline dry batteries can have a thinner separator, and the thinner separator allows an increase in the filling capacity of the electroactive material and an improvement in discharge performance.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, even when a chelating agent is added to an alkaline dry battery, in order to improve the discharge performance, it is necessary to make the separator thinner.

[0005] The disclosed technology has been made in view of the above and aims to provide a battery and a battery manufacturing method that improves discharge performance. [Means for solving the problem]

[0006] One aspect of this disclosure Alkaline primary The battery comprises a positive electrode containing manganese dioxide and graphite, a negative electrode containing zinc, an electrolyte in which the positive electrode and the negative electrode are immersed, and polyethyleneimine contained in the negative electrode. The ratio of the mass of polyethyleneimine to the mass of zinc is 50 ppm or more and 1000 ppm or less. The molecular weight of the polyethyleneimine is 300 or more and 70,000 or less. [Effects of the Invention]

[0007] The disclosed battery and battery manufacturing method can improve discharge performance. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a perspective cross-sectional view showing a battery according to an embodiment. [Figure 2] Figure 2 is a flowchart showing the battery manufacturing method according to the embodiment. [Modes for carrying out the invention]

[0009] The battery according to the embodiments disclosed herein will be described below with reference to the drawings. However, the technology of this disclosure is not limited by the following description. Furthermore, the same reference numerals are used for identical components, and redundant descriptions are omitted.

[0010] [Battery 1 of the embodiment] The battery 1 of this embodiment is an alkaline dry cell and comprises a battery case 2, a positive electrode 3, a negative electrode 5, a current collector rod 6, and a separator 7, as shown in Figure 1. Figure 1 is a perspective cross-sectional view showing the battery 1 of this embodiment. The battery case 2 comprises a positive electrode can 11, a negative electrode terminal plate 12, and a sealing gasket 14. The positive electrode can 11 is formed from a conductor, exemplified by metal. The positive electrode can 11 is formed in a bottomed cylindrical shape and comprises a side portion 15 and a bottom portion 16. The side portion 15 is formed from a bent plate that follows the side of the cylinder. The bottom portion 16 is positioned along one bottom surface of the cylinder. The bottom portion 16 is integrally connected to the side portion 15 such that the edge of the bottom portion 16 is adjacent to one end of the side portion 15.

[0011] The bottom portion 16 has irregularities formed on it, and a positive electrode terminal portion 17 is formed in the center of the bottom portion 16. The positive electrode terminal portion 17 is formed to protrude from the inside to the outside of the positive electrode can 11. An opening 18 is formed in the positive electrode can 11. The opening 18 is formed in the part of the side portion 15 that corresponds to the bottom surface of the other cylindrical part. The inside of the positive electrode can 11 is connected to the outside of the positive electrode can 11 through the opening 18.

[0012] The negative electrode terminal plate 12 is formed from a conductor, exemplified by metal, and is generally disc-shaped. The negative electrode terminal plate 12 is positioned along the other bottom surface of the cylinder so as to close the opening 18 of the positive electrode can 11. Inside the battery case 2, an internal space 23 is formed surrounded by the positive electrode can 11 and the negative electrode terminal plate 12, as the negative electrode terminal plate 12 closes the opening 18.

[0013] The sealing gasket 14 is formed from an insulator, exemplified by resin, and is generally ring-shaped. The sealing gasket 14 surrounds the edge of the negative electrode terminal plate 12 and is positioned in the opening 18 of the positive electrode can 11. The sealing gasket 14 is sandwiched between the edge of the negative electrode terminal plate 12 and the positive electrode can 11, sealing the gap formed between the edge of the negative electrode terminal plate 12 and the positive electrode can 11. The negative electrode terminal plate 12 is fixed to the positive electrode can 11 via the sealing gasket 14, as the sealing gasket 14 is sandwiched between the edge of the negative electrode terminal plate 12 and the positive electrode can 11. The negative electrode terminal plate 12 is electrically insulated from the positive electrode can 11 via the sealing gasket 14, as the sealing gasket 14 is sandwiched between the edge of the negative electrode terminal plate 12 and the positive electrode can 11.

[0014] The battery case 2 further includes an outer label 19. The outer label 19 is formed from a heat-shrinkable film. The heat-shrinkable film is an insulator and shrinks when heated. The outer label 19 covers the area of ​​the surface of the battery case 2 that is exposed to the outside, excluding the negative terminal plate 12 and the positive terminal portion 17.

[0015] The positive electrode 3 is formed from a positive electrode mixture. The positive electrode mixture contains a positive electrode active material, a binder, and an aqueous potassium hydroxide solution. The positive electrode active material contains manganese dioxide (MnO2) and graphite (C). The binder, for example, contains a polymer compound and adheres the powders formed from the positive electrode active material to each other to form a solid. The positive electrode 3 is formed in a tubular shape and is placed in the internal space 23 of the battery case 2. The positive electrode 3 is in close contact with the inner circumferential surface of the side portion 15 of the positive electrode can 11 so that the positive electrode active material is electrically connected to the positive electrode can 11.

[0016] The negative electrode 5 is formed from a negative electrode active material and is formed in a gel shape. The negative electrode active material contains zinc powder and an aqueous potassium hydroxide solution. The negative electrode 5 further contains polyethyleneimine. The molecular weight of the polyethyleneimine is, for example, 300 or more and 70,000 or less. The negative electrode 5 is disposed inside the positive electrode 3 in the internal space 23 of the battery case 2. Note that the zinc powder contained in the negative electrode active material may be replaced with zinc alloy powder formed from a zinc alloy containing zinc.

[0017] The current collector rod 6 is formed from a conductor and is formed in a rod shape. The current collector rod 6 is disposed in the internal space 23 along the central axis of the cylinder along which the side surface portion 15 extends. The current collector rod 6 is further embedded in the negative electrode 5 so that the current collector rod 6 is electrically connected to the negative electrode active material of the negative electrode 5. The current collector rod 6 further penetrates the center of the sealing gasket 14. One end of the current collector rod 6 is joined to the negative electrode terminal plate 12 so that the current collector rod 6 is electrically connected to the negative electrode terminal plate 12.

[0018] The separator 7 is formed from an insulator exemplified by vinylon, pulp, or the like. The separator 7 is formed in a bottomed hollow cylindrical shape and includes a side surface portion 25 and a bottom surface portion 26. The side surface portion 25 is disposed between the positive electrode 3 and the negative electrode 5 in the internal space 23. The bottom surface portion 26 is disposed between the negative electrode 5 and the bottom surface portion 16 of the positive electrode can 11 in the internal space 23. The bottom surface portion 26 is integrally connected to one end of the side surface portion 25 so that the region where the negative electrode 5 is disposed in the internal space 23 is separated from the region where the positive electrode 3 and the positive electrode can 11 are disposed in the internal space 23. By being disposed in this manner, the separator 7 separates the positive electrode 3 and the negative electrode 5 and separates the negative electrode 5 and the positive electrode can 11. The negative electrode 5 is electrically insulated from the positive electrode 3 because the separator 7 separates the positive electrode 3 and the negative electrode 5, and is electrically insulated from the positive electrode can 11 because the separator 7 separates the negative electrode 5 and the positive electrode can 11.

[0019] The battery 1 further includes an electrolyte. The electrolyte is formed from an aqueous solution containing potassium hydroxide KOH. The electrolyte further contains polyethyleneimine. The ratio of the sum of the masses of polyethyleneimine contained in the negative electrode 5 and the electrolyte to the mass of zinc contained in the negative electrode 5 is 50 ppm or more and 1000 ppm or less. The electrolyte is disposed in the internal space 23 so that the positive electrode 3 and the negative electrode 5 are immersed in the electrolyte, penetrates the separator 7, and penetrates the positive electrode 3.

[0020] [Method for manufacturing a battery according to an embodiment] FIG. 2 is a flowchart showing a method for manufacturing a battery according to an embodiment. The method for manufacturing a battery according to the embodiment is a method for manufacturing the battery 1. In the method for manufacturing a battery, a positive electrode mixture is prepared, and a positive electrode can 11 is prepared. The positive electrode mixture is subjected to molding (step S1) and formed on the positive electrode 3. The positive electrode 3 is inserted into the inside of the positive electrode can 11 so that the positive electrode 3 fits into the positive electrode can 11, that is, the outer peripheral surface of the positive electrode 3 contacts the inner peripheral surface of the positive electrode can 11 (step S2).

[0021] In the method for manufacturing a battery, a separator 7 is further prepared. The separator 7 is subjected to molding (step S3) and formed into a bottomed hollow cylindrical shape. After the positive electrode 3 is inserted into the inside of the positive electrode can 11 and after the separator 7 is formed into a bottomed hollow cylindrical shape, the separator 7 is inserted inside the positive electrode 3 (step S4).

[0022] In the method for manufacturing a battery, an electrolyte is further prepared. The electrolyte is prepared in an aqueous solution in which potassium hydroxide KOH having a predetermined concentration is dissolved. A predetermined amount of polyethyleneimine is added to the electrolyte (step S5). Note that the process of step S5 may be omitted when polyethyleneimine is added to the negative electrode 5. After the separator 7 is inserted inside the positive electrode 3, the electrolyte is injected inside the positive electrode 3 (step S6). By injecting the electrolyte inside the positive electrode 3, the electrolyte penetrates the separator 7 and penetrates the positive electrode 3.

[0023] In the battery manufacturing method, a negative electrode 5 is further prepared. The negative electrode 5 is prepared in a gel state using zinc powder and an aqueous potassium hydroxide solution. A predetermined amount of polyethyleneimine is added to the negative electrode 5 (step S7). Note that the process in step S7 may be omitted when polyethyleneimine is added to the electrolyte. After the electrolyte has permeated the separator 7 and the positive electrode 3, a predetermined amount of the negative electrode 5 is injected into the inside of the separator 7 (step S8).

[0024] In the battery manufacturing method, a current collector rod 6, a negative electrode terminal plate 12, and a sealing gasket 14 are further prepared. The current collector is manufactured by joining the current collector rod 6 to the negative electrode terminal plate 12 so that the current collector rod 6 makes electrical contact with the negative electrode terminal plate 12, and by joining the sealing gasket 14 to the negative electrode terminal plate 12 so that the edge of the negative electrode terminal plate 12 is covered by the sealing gasket 14. After the negative electrode 5 is injected, the current collector is attached to the positive electrode can 11 so that the current collector rod 6 joined to the negative electrode terminal plate 12 is embedded in the negative electrode 5, and so that the negative electrode terminal plate 12 and the sealing gasket 14 close the opening 18. After the current collector rod 6, the negative electrode terminal plate 12, and the sealing gasket 14 are attached to the positive electrode can 11, the portion of the positive electrode can 11 near the opening 18 is crimped (step S9) so that the gap formed between the negative electrode terminal plate 12 and the positive electrode can 11 is sealed by the sealing gasket 14. As the positive electrode can 11 is crimped, the sealing gasket 14 deforms, fixing the current collector rod 6, the negative electrode terminal plate 12, and the sealing gasket 14 to the positive electrode can 11, and sealing the internal space 23 from the outside.

[0025] In the battery manufacturing method, an outer label 19 is further prepared. The outer label 19 is wrapped around the battery case 2 after the current collector rod 6, the negative electrode terminal plate 12, and the sealing gasket 14 are fixed to the positive electrode can 11, so as to cover the area of ​​the surface of the battery case 2 excluding the negative electrode terminal plate 12 and the positive electrode terminal portion 17 (step S10). After the outer label 19 is wrapped around the battery case 2, the outer label 19 is heated, shrunk, and attached to the battery case 2 to manufacture the battery 1. According to such a battery manufacturing method, the battery 1 can be properly manufactured so that polyethyleneimine is appropriately added to the negative electrode 5 or the electrolyte.

[0026] [Evaluation test of battery 1] To confirm the effectiveness of battery 1 in the embodiment, multiple battery samples were prepared, and multiple evaluation tests were performed on each of the multiple battery samples. Table 1 shows the multiple preparation conditions and multiple evaluation results corresponding to the multiple battery samples. [Table 1] The multiple battery samples include the battery of Comparative Example 1, the battery of Comparative Example 2, the battery of Comparative Example 3, the battery of Example 1, the battery of Example 2, the battery of Example 3, the battery of Example 4, the battery of Example 5, and the battery of Example 6.

[0027] Multiple battery samples are prepared under different preparation conditions. These preparation conditions are indicated by the type of chelating agent, its addition location, and the amount added. The chelating agent type indicates "polyethyleneimine," "EDTA," or "glycine." Specifically, when the chelating agent type of a battery sample indicates "polyethyleneimine," it means that polyethyleneimine is added to the negative electrode 5 or electrolyte of that battery sample. When the chelating agent type of a battery sample indicates "EDTA," it means that ethylenediaminetetraacetic acid (EDTA) is added to the negative electrode 5 or electrolyte of that battery sample, and polyethyleneimine is not added to the negative electrode 5 or electrolyte of that battery sample. When the chelating agent type of a battery sample indicates "glycine," it means that glycine is added to the negative electrode 5 or electrolyte of that battery sample, and polyethyleneimine is not added to the negative electrode 5 or electrolyte of that battery sample.

[0028] The location of addition indicates either the "negative electrode" or the "electrolyte." That is, when the location of addition for a battery sample indicates "negative electrode," it indicates that the chelating agent has been added to the negative electrode 5 of that battery sample, and that the chelating agent has not been added to the electrolyte of that battery sample. When the location of addition for a battery sample indicates "electrolyte," it indicates that the chelating agent has been added to the electrolyte of that battery sample, and that the chelating agent has not been added to the negative electrode 5 of that battery sample.

[0029] The amount added to a particular battery sample indicates the total amount of chelating agent added to the negative electrode 5 or electrolyte of that battery sample, and represents the ratio of the total amount of chelating agent added to the negative electrode 5 or electrolyte of that battery sample to the mass of zinc contained in the negative electrode 5 of that battery sample. In other words, when the amount added to a particular battery sample shows "X ppm", it indicates that the value of X is equal to the value obtained by dividing the mass of chelating agent added to the negative electrode 5 and electrolyte of that battery sample by the mass of zinc contained in the negative electrode 5 of that battery sample, and then multiplying that value by one million.

[0030] The multiple battery samples are prepared similarly to each other, except that their preparation conditions differ. Specifically, the multiple battery samples are prepared so that the battery size is LR6 (AA battery), with the positive electrode 3, current collector rod 6, separator 7, positive electrode casing 11, negative electrode terminal plate 12, and sealing gasket 14 being the same. The molecular weight of the polyethyleneimine added to the negative electrode 5 or electrolyte is approximately 1800.

[0031] The battery of Comparative Example 1 is manufactured so that no chelating agent is added to the negative electrode 5 and no chelating agent is added to the electrolyte.

[0032] The type of chelating agent in Comparative Example 2's battery is indicated as "EDTA". The location of addition in Comparative Example 2's battery is indicated as the "negative electrode". The amount added in Comparative Example 2's battery is indicated as "300 ppm". In other words, Comparative Example 2's battery is manufactured so that 300 ppm of ethylenediaminetetraacetic acid is added to the negative electrode 5 relative to the zinc contained in the negative electrode 5, and so that no chelating agent is added to the electrolyte.

[0033] The type of chelating agent in Comparative Example 3's battery is "glycine." The location of addition in Comparative Example 3's battery is the "negative electrode." The amount added in Comparative Example 3's battery is "300 ppm." In other words, Comparative Example 3's battery is manufactured so that 300 ppm of glycine is added to the negative electrode 5 relative to the zinc contained in the negative electrode 5, and no chelating agent is added to the electrolyte.

[0034] The type of chelating agent in the battery of Example 1 is indicated as "polyethyleneimine". The location of addition in the battery of Example 1 is indicated as the "negative electrode". The amount of addition in the battery of Example 1 is indicated as "30 ppm". In other words, the battery of Example 1 is manufactured so that 30 ppm of polyethyleneimine is added to the negative electrode 5 relative to the zinc contained in the negative electrode 5, and so that no chelating agent is added to the electrolyte.

[0035] The type of chelating agent in the battery of Example 2 is indicated as "polyethyleneimine". The location of addition in the battery of Example 2 is indicated as the "negative electrode". The amount of addition in the battery of Example 2 is indicated as "50 ppm". In other words, the battery of Example 2 is manufactured so that 50 ppm of polyethyleneimine is added to the negative electrode 5 relative to the zinc contained in the negative electrode 5, and so that no chelating agent is added to the electrolyte.

[0036] The type of chelating agent in the battery of Example 3 is "polyethyleneimine". The location of addition in the battery of Example 3 is the "negative electrode". The amount of addition in the battery of Example 3 is "300 ppm". In other words, the battery of Example 3 is manufactured so that 300 ppm of polyethyleneimine is added to the negative electrode 5 relative to the zinc contained in the negative electrode 5, and no chelating agent is added to the electrolyte.

[0037] The type of chelating agent in the battery of Example 4 is "polyethyleneimine". The location of addition in the battery of Example 4 is the "negative electrode". The amount added in the battery of Example 4 is "1000 ppm". In other words, the battery of Example 4 is manufactured so that 1000 ppm of polyethyleneimine is added to the negative electrode 5 relative to the zinc contained in the negative electrode 5, and so that no chelating agent is added to the electrolyte.

[0038] The type of chelating agent in the battery of Example 5 is "polyethyleneimine". The location of addition in the battery of Example 5 is the "negative electrode". The amount added in the battery of Example 5 is "1500 ppm". In other words, the battery of Example 5 is manufactured so that 1500 ppm of polyethyleneimine is added to the negative electrode 5 relative to the zinc contained in the negative electrode 5, and no chelating agent is added to the electrolyte.

[0039] The type of chelating agent in the battery of Example 6 is indicated as "polyethyleneimine". The location of addition in the battery of Example 6 is indicated as the electrolyte. The amount added in the battery of Example 6 is indicated as "300 ppm". In other words, the battery of Example 1 is manufactured so that 300 ppm of polyethyleneimine is added to the electrolyte relative to the zinc contained in the negative electrode 5, and so that no chelating agent is added to the negative electrode 5.

[0040] The multiple evaluation results include multiple light-load intermittent discharge test results, multiple medium-load pulse discharge test results, multiple first heavy-load pulse discharge test results, and multiple second heavy-load pulse discharge test results. Multiple light-load intermittent discharge test results correspond to multiple battery samples. The light-load intermittent discharge test result corresponding to a particular battery sample is derived by performing a light-load intermittent discharge test on that battery sample. In a light-load intermittent discharge test performed on a battery sample, an 8-hour discharge pattern is repeatedly executed until the battery voltage falls below the cutoff voltage of 1.0V, and the light-load intermittent discharge time is derived. The 8-hour discharge pattern consists of a 1-hour discharge period and a 7-hour rest period. During the 1-hour discharge period, the battery sample is electrically connected to a load so that it discharges at 50mA. During the 7-hour rest period, the battery sample is electrically isolated from the load so that it does not discharge. The light-load intermittent discharge time indicates the amount of time the battery sample was discharged before its battery voltage fell below the cutoff voltage of 1.0V.

[0041] The light-load intermittent discharge test result corresponding to a particular battery sample among multiple light-load intermittent discharge test results is shown as the value obtained by dividing the average light-load intermittent discharge time of that battery sample by the average light-load intermittent discharge time of the battery in Comparative Example 1, and then multiplying the result by 100. The average light-load intermittent discharge time of that battery sample represents the average of multiple light-load intermittent discharge times derived for each of the multiple batteries prepared as that battery sample. The multiple light-load intermittent discharge test results indicate that the battery sample corresponding to the light-load intermittent discharge test result with a larger value has better light-load discharge performance.

[0042] Multiple light-load intermittent discharge test results show that the light-load intermittent discharge test results of the batteries in Comparative Examples 2 and 3 are equivalent to those of the battery in Comparative Example 1, and that the light-load discharge performance of the batteries in Comparative Examples 2 and 3 is equivalent to that of the battery in Comparative Example 1. In other words, multiple light-load intermittent discharge test results show that even if a chelating agent different from polyethyleneimine is added to the negative electrode 5 or electrolyte of the battery, the light-load discharge performance of the battery does not improve when the thickness of the separator 7 is the same.

[0043] Multiple light-load intermittent discharge test results show that the light-load intermittent discharge test results for the batteries of Examples 1 to 6 were greater than those for the batteries of Comparative Examples 1 to 3, indicating that the light-load discharge performance of the batteries of Examples 1 to 6 is better than that of the batteries of Comparative Examples 1 to 3. In other words, the results of multiple light-load intermittent discharge tests indicate that the light-load discharge performance of batteries in which polyethyleneimine is added to the negative electrode 5 or electrolyte is better than that of batteries in which polyethyleneimine is not added to the negative electrode 5 or electrolyte.

[0044] Multiple light-load intermittent discharge test results indicate that the light-load intermittent discharge test results for the battery in Example 4 were greater than those for the batteries in Examples 1-3, and greater than those for the battery in Example 5. In other words, multiple light-load intermittent discharge test results indicate that when the ratio of polyethyleneimine mass to zinc mass is 1000 ppm or less, the light-load discharge performance of the battery tends to decrease as the amount of polyethyleneimine decreases. Furthermore, multiple light-load intermittent discharge test results indicate that when the ratio of polyethyleneimine mass to zinc mass is 1000 ppm or more, the light-load discharge performance of the battery tends to decrease as the amount of polyethyleneimine increases.

[0045] Multiple medium-load pulsed discharge test results correspond to multiple battery samples. The medium-load pulsed discharge test result corresponding to a particular battery sample is derived by performing a medium-load pulsed discharge test on that battery sample. In the medium-load pulsed discharge test performed on a particular battery sample, an 8-hour discharge pattern is repeatedly executed daily until the battery voltage falls below the cutoff voltage of 0.9V, and the medium-load pulsed discharge time is derived. The 8-hour discharge pattern consists of eight 1-hour discharge patterns. The 1-hour discharge pattern consists of a 4-minute discharge period and a 56-minute rest period. During the 4-minute discharge period, the battery sample is electrically connected to a 3.9Ω load. During the 56-minute rest period, the battery sample is electrically isolated from the load to prevent further discharge. The medium-load pulsed discharge time indicates the amount of time the battery sample was discharged before its battery voltage fell below the cutoff voltage of 0.9V.

[0046] The medium-load pulse discharge test result corresponding to a particular battery sample among multiple medium-load pulse discharge test results is shown as the value obtained by dividing the average medium-load pulse discharge time of that battery sample by the average medium-load pulse discharge time of the battery in Comparative Example 1, and then multiplying the result by 100. The average medium-load pulse discharge time of that battery sample represents the average of multiple medium-load pulse discharge times derived for each of the multiple batteries prepared as that battery sample. The multiple medium-load pulse discharge test results indicate that the battery sample corresponding to the medium-load pulse discharge test result with a larger value has better medium-load discharge performance.

[0047] Multiple medium-load pulse discharge test results show that the medium-load pulse discharge test results of the batteries in Comparative Examples 2 and 3 are equivalent to those of the battery in Comparative Example 1, and that the medium-load discharge performance of the batteries in Comparative Examples 2 and 3 is equivalent to that of the battery in Comparative Example 1. In other words, the results of multiple medium-load pulse discharge tests indicate that even when a chelating agent different from polyethyleneimine is added to the negative electrode 5 or electrolyte of the battery, the medium-load discharge performance of the battery does not improve when the thickness of the separator 7 is the same.

[0048] Multiple medium-load pulse discharge test results indicate that the medium-load pulse discharge test results of the batteries in Examples 1 to 6 were greater than those of the batteries in Comparative Examples 1 to 3, and that the medium-load discharge performance of the batteries in Examples 1 to 6 is better than that of the batteries in Comparative Examples 1 to 3. In other words, multiple medium-load pulse discharge test results indicate that the medium-load discharge performance of batteries in which polyethyleneimine is added to the negative electrode 5 or electrolyte is better than that of batteries in which polyethyleneimine is not added to the negative electrode 5 or electrolyte.

[0049] Multiple medium-load pulse discharge test results indicate that the medium-load pulse discharge test results for batteries in Examples 3 and 6 were greater than those for batteries in Examples 1 and 2, and greater than those for batteries in Examples 4 and 5. In other words, multiple medium-load pulse discharge test results indicate that when the ratio of polyethyleneimine mass to zinc mass is 300 ppm or less, the medium-load discharge performance of the battery tends to decrease as the amount of polyethyleneimine decreases. Furthermore, multiple medium-load pulse discharge test results indicate that when the ratio of polyethyleneimine mass to zinc mass is 300 ppm or more, the medium-load discharge performance of the battery tends to decrease as the amount of polyethyleneimine increases.

[0050] Multiple first heavy load pulse discharge test results correspond to multiple battery samples. The first heavy load pulse discharge test result corresponding to a particular battery sample among the multiple first heavy load pulse discharge test results is derived by performing the first heavy load pulse discharge test on that battery sample. In the first heavy load pulse discharge test performed on a particular battery sample, an 8-hour discharge pattern is repeatedly performed daily until the battery voltage of that battery sample falls below the cutoff voltage of 1.1V, and the first heavy load pulse discharge time is derived. The 8-hour discharge pattern consists of eight 1-hour discharge patterns. The 1-hour discharge pattern consists of a 2-minute discharge period and a 58-minute rest period. During the 2-minute discharge period, the battery sample is electrically connected to the load so that it discharges at 750mW. During the 58-minute rest period, the battery sample is electrically isolated from the load so that it does not discharge. The first heavy-load pulse discharge time indicates the time the battery sample was discharged before its battery voltage fell below the termination voltage of 1.1V.

[0051] The first heavy load pulse discharge test result corresponding to a particular battery sample among multiple first heavy load pulse discharge test results is shown as the value obtained by dividing the average first heavy load pulse discharge time of that battery sample by the average first heavy load pulse discharge time of the battery in Comparative Example 1, and then multiplying the result by 100. The average first heavy load pulse discharge time of that battery sample represents the average of multiple first heavy load pulse discharge times derived for each of the multiple batteries prepared as that battery sample. The multiple first heavy load pulse discharge test results indicate that the battery sample corresponding to the first heavy load pulse discharge test result showing a larger value has better heavy load discharge performance.

[0052] Multiple first heavy-load pulse discharge test results show that the first heavy-load pulse discharge test results of the batteries in Comparative Examples 2 and 3 are equivalent to those of the battery in Comparative Example 1, and that the heavy-load discharge performance of the batteries in Comparative Examples 2 and 3 is equivalent to that of the battery in Comparative Example 1. In other words, multiple first heavy-load pulse discharge test results show that even if a chelating agent different from polyethyleneimine is added to the negative electrode 5 or electrolyte of the battery, the heavy-load discharge performance of the battery does not improve when the thickness of the separator 7 is the same.

[0053] Multiple first heavy-load pulse discharge test results indicate that the first heavy-load pulse discharge test results for the batteries of Examples 1 to 6 were greater than those for the batteries of Comparative Examples 1 to 3, demonstrating that the heavy-load discharge performance of the batteries of Examples 1 to 6 is better than that of the batteries of Comparative Examples 1 to 3. In other words, multiple first heavy-load pulse discharge test results indicate that the heavy-load discharge performance of batteries in which polyethyleneimine is added to the negative electrode 5 or electrolyte is better than that of batteries in which polyethyleneimine is not added to the negative electrode 5 or electrolyte.

[0054] Multiple first-load pulse discharge test results indicate that the first-load pulse discharge test results for batteries in Examples 3-4 and 6 were greater than those for batteries in Examples 1-2 and greater than those for battery in Example 5. In other words, multiple first-load pulse discharge test results indicate that when the ratio of polyethyleneimine mass to zinc mass is 300 ppm or less, the discharge performance of the battery under first load tends to decrease as the amount of polyethyleneimine decreases. Furthermore, multiple first-load pulse discharge test results indicate that when the ratio of polyethyleneimine mass to zinc mass is 1000 ppm or more, the discharge performance of the battery under first load tends to decrease as the amount of polyethyleneimine increases.

[0055] The results of multiple secondary heavy-load pulsed discharge tests correspond to multiple battery samples. The secondary heavy-load pulsed discharge test results corresponding to a particular battery sample are derived by performing the secondary heavy-load pulsed discharge test on that battery sample. In the secondary heavy-load pulsed discharge test performed on a particular battery sample, a 1-hour discharge pattern is repeatedly executed until the battery voltage of that battery sample falls below the cutoff voltage of 1.05V, and the secondary heavy-load pulsed discharge time is derived. The 1-hour discharge pattern consists of a 5-minute discharge period and a 55-minute rest period. During the 5-minute discharge period, a 30-second discharge pattern is repeated 10 times. The 30-second discharge pattern consists of a 2-second discharge period and a 28-second discharge period. During the 2-second discharge period, the battery sample is electrically connected to a 1500mW load. The 28-second discharge period begins immediately after the end of the 2-second discharge period. During the 28-second discharge period, the battery sample is electrically connected to a 650mW load for 28 seconds. During the 55-minute rest period, the battery sample is electrically isolated from the load to prevent further discharge. The second heavy-load pulse discharge time indicates the time the battery sample was discharged before its battery voltage fell below the cutoff voltage of 1.05V.

[0056] The results of the secondary heavy load pulse discharge test for a particular battery sample among the multiple secondary heavy load pulse discharge test results show the value obtained by dividing the average secondary heavy load pulse discharge time of that battery sample by the average secondary heavy load pulse discharge time of the battery in Comparative Example 1, and then multiplying the result by 100. The average secondary heavy load pulse discharge time of that battery sample represents the average of multiple secondary heavy load pulse discharge times derived for each of the multiple batteries manufactured as that battery sample. The multiple secondary heavy load pulse discharge test results indicate that the battery sample corresponding to the secondary heavy load pulse discharge test result showing a larger value has better discharge performance under heavy load.

[0057] Multiple secondary heavy-load pulse discharge test results show that the secondary heavy-load pulse discharge test results of the batteries in Comparative Examples 2 and 3 are equivalent to those of the battery in Comparative Example 1, and that the heavy-load discharge performance of the batteries in Comparative Examples 2 and 3 is equivalent to that of the battery in Comparative Example 1. In other words, multiple secondary heavy-load pulse discharge test results show that even if a chelating agent different from polyethyleneimine is added to the negative electrode 5 or electrolyte of the battery, the heavy-load discharge performance of the battery does not improve when the thickness of the separator 7 is the same.

[0058] Multiple secondary heavy-load pulse discharge test results indicate that the secondary heavy-load pulse discharge test results for the batteries of Examples 1 to 6 were greater than those for the batteries of Comparative Examples 1 to 3, demonstrating that the heavy-load discharge performance of the batteries of Examples 1 to 6 is better than that of the batteries of Comparative Examples 1 to 3. In other words, multiple secondary heavy-load pulse discharge test results indicate that the heavy-load discharge performance of batteries in which polyethyleneimine is added to the negative electrode 5 or electrolyte is better than that of batteries in which polyethyleneimine is not added to the negative electrode 5 or electrolyte.

[0059] Multiple double-load pulse discharge test results indicate that the double-load pulse discharge test results for batteries in Examples 3 and 6 were greater than those for batteries in Examples 1 and 2, and greater than those for batteries in Examples 4 and 5. In other words, multiple double-load pulse discharge test results indicate that when the ratio of polyethyleneimine mass to zinc mass is 300 ppm or less, the discharge performance of the battery under double load tends to decrease as the amount of polyethyleneimine decreases. Furthermore, multiple double-load pulse discharge test results indicate that when the ratio of polyethyleneimine mass to zinc mass is 300 ppm or more, the discharge performance of the battery under double load tends to decrease as the amount of polyethyleneimine increases.

[0060] Multiple evaluation results indicate that batteries with polyethyleneimine added to the negative electrode 5 or electrolyte have better discharge performance than batteries without polyethyleneimine added to the negative electrode 5 or electrolyte. The chelating agent added to the negative electrode 5 or electrolyte is zincate ions Zn(OH)4, which are produced during battery discharge. 2- It is believed that by forming a complex with it, the progress of the next chemical reaction equation, in which zinc oxide (ZnO) precipitates, can be slowed down. Zn(OH)4 2- →ZnO+H2O+2OH - The precipitated zinc oxide (ZnO) forms a passive film covering the surface of the zinc powder. Polyethyleneimine is thought to suppress the formation of zinc oxide (ZnO) in the passive film more effectively than other chelating agents. Furthermore, the electrical conductivity of zinc oxide (ZnO) precipitated in the presence of polyethyleneimine is thought to be higher than that of zinc oxide (ZnO) precipitated in the absence of polyethyleneimine. As a result, battery 1 can allow more metallic zinc to participate in the battery reaction, improving its discharge performance. Multiple evaluation results further indicate that batteries with a polyethyleneimine mass-to-zinc mass ratio within the range of 300 ppm to 1000 ppm have better discharge performance than batteries with a ratio outside that range.

[0061] [Effects of Battery 1 in the Embodiment] The battery 1 of the embodiment comprises a positive electrode 3 containing manganese dioxide and graphite, a negative electrode 5 containing zinc, an electrolyte in which the positive electrode 3 and negative electrode 5 are immersed, and polyethyleneimine contained in the negative electrode 5. Furthermore, the battery 1 of the embodiment comprises a positive electrode 3 containing manganese dioxide and graphite, a negative electrode 5 containing zinc, an electrolyte in which the positive electrode 3 and negative electrode 5 are immersed, and polyethyleneimine contained in the electrolyte. In this case, the battery 1 can improve its discharge performance.

[0062] Incidentally, in the batteries of Examples 1 to 6 described above, polyethyleneimine is added to either the negative electrode 5 or the electrolyte, but not to the other. However, polyethyleneimine may be added to both the negative electrode 5 and the electrolyte. Battery 1 also exhibits improved discharge performance when polyethyleneimine is added to both the negative electrode 5 and the electrolyte.

[0063] The battery manufacturing method of the embodiment comprises preparing a positive electrode 3 containing manganese dioxide and graphite, preparing a negative electrode 5 containing zinc and with polyethyleneimine added, and assembling a battery 1 in which the positive electrode 3 and the negative electrode 5 are immersed in an electrolyte. Alternatively, the battery manufacturing method of the embodiment comprises preparing a positive electrode 3 containing manganese dioxide and graphite, preparing a negative electrode 5 containing zinc, preparing an electrolyte with polyethyleneimine added, and assembling a battery 1 in which the positive electrode 3 and the negative electrode 5 are immersed in an electrolyte. A battery 1 manufactured by such a battery manufacturing method can have its discharge performance improved by containing polyethyleneimine in the negative electrode 5 or the electrolyte.

[0064] Incidentally, in the battery of the previously described example, polyethyleneimine with a molecular weight of approximately 1800 is added to the negative electrode 5 or the electrolyte. However, polyethyleneimine with a molecular weight different from 1800 may also be added to the negative electrode 5 or the electrolyte. Further tests have been conducted to confirm the effect of batteries in which polyethyleneimine with a molecular weight different from 1800 is added to the negative electrode 5 or the electrolyte. In these tests, five types of battery samples were prepared, each with five different polyethyleneimines with molecular weights of approximately 300, 600, 1200, 1800, and 70000 added. The results of these tests show that the discharge performance of batteries with polyethyleneimine with molecular weights different from 1800 is improved, similar to batteries with polyethyleneimine with a molecular weight of approximately 1800. The test results further show that the discharge performance tends to improve as the polyethyleneimine with a smaller molecular weight is added. The test results further indicate that the larger the molecular weight of polyethyleneimine added to the battery, the more polyethyleneimine needs to be added to the negative electrode 5 or electrolyte. In other words, even when polyethyleneimine with a molecular weight different from 1800 is added to the negative electrode 5 or electrolyte, the battery can improve its discharge performance in the same way as a battery with polyethyleneimine with a molecular weight of approximately 1800 added to the negative electrode 5 or electrolyte.

[0065] Although examples have been described above, the examples are not limited to those described above. Furthermore, the components described above include those that can be easily imagined by a person skilled in the art, those that are substantially the same, and those that fall within the so-called equivalent range. Moreover, the components described above can be combined as appropriate. Furthermore, at least one of various omissions, substitutions, and modifications of the components can be made without departing from the gist of the examples. [Explanation of symbols]

[0066] 1:Battery 3: Positive electrode 5: Negative electrode 7: Separator

Claims

1. A positive electrode containing manganese dioxide and graphite, A negative electrode containing zinc and electrolyte, A separator that separates the positive electrode and the negative electrode, The electrolyte in which the positive electrode and the separator are immersed, The negative electrode comprises polyethyleneimine contained in the electrolyte, The ratio of the mass of polyethyleneimine to the mass of zinc is 50 ppm or more and 1000 ppm or less. The molecular weight of the polyethyleneimine is 300 or more and 70,000 or less. Alkaline primary battery.

2. A positive electrode containing manganese dioxide and graphite, A negative electrode containing zinc and electrolyte, A separator that separates the positive electrode and the negative electrode, An electrolyte in which the positive electrode and the negative electrode are immersed, The electrolyte solution comprises polyethyleneimine, The ratio of the mass of polyethyleneimine to the mass of zinc is 50 ppm or more and 1000 ppm or less. The molecular weight of the polyethyleneimine is 300 or more and 70,000 or less. Alkaline primary battery.

3. A positive electrode containing manganese dioxide and graphite, A negative electrode containing zinc and electrolyte, A separator that separates the positive electrode and the negative electrode, An electrolyte in which the positive electrode and the negative electrode are immersed, The electrolyte and polyethyleneimine contained in the electrolyte in the negative electrode are provided. The ratio of the mass of polyethyleneimine to the mass of zinc is 50 ppm or more and 1000 ppm or less. The molecular weight of the polyethyleneimine is 300 or more and 70,000 or less. Alkaline primary battery.

4. Prepare a positive electrode containing manganese dioxide and graphite, Prepare a negative electrode containing zinc and with polyethyleneimine added, The assembly of an alkaline primary battery in which the positive electrode and the negative electrode are immersed in an electrolyte, The ratio of the mass of polyethyleneimine to the mass of zinc is 50 ppm or more and 1000 ppm or less. The molecular weight of the polyethyleneimine is 300 or more and 70,000 or less. Battery manufacturing method.

5. Prepare a positive electrode containing manganese dioxide and graphite, Prepare a negative electrode containing zinc, Prepare an electrolyte solution to which polyethyleneimine has been added, The assembly of an alkaline primary battery in which the positive electrode and the negative electrode are immersed in the electrolyte, The ratio of the mass of polyethyleneimine to the mass of zinc is 50 ppm or more and 1000 ppm or less. The molecular weight of the polyethyleneimine is 300 or more and 70,000 or less. Battery manufacturing method.

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